1. Field of the Invention:
The present invention relates generally to a process for treating oil-contaminated particulates, such as drilling cuttings, and particularly those in which the salt content is high enough to present a disposal problem. More specifically, the invention relates to a staged washing and solids removal process for treating particulate materials such as drilling cuttings or drilling mud pit residues to produce a source of desalinated solid particles suitable for various uses or disposal as a non-hazardous waste.
2. Description of the Prior Art:
Oil and gas well drilling fluids, known in the industry as "muds", have been known for many years. The return of this mud from the borehole where the drilling occurs includes cuttings and other materials that were not originally present in the mud. In an oil-based mud drilling operation, there are typically two liquids (diesel and water) that normally become waste and are environmentally hazardous. When drilling with oil-based mud, the drilling rig must be washed with diesel in order not to contaminate the mud with water. Other sources of contamination exist on the rig, as well.
In various regions, tanks are used for storing drilling fluids and cuttings where reserve pits are not permitted. Also, removal may be required from presently existing reserve pits. In the reserve pits, the used drilling fluid contents are typically contaminated by, for example, top soil used in constructing the pit. Unclaimed mud, diesel and other effluents from the well may be dumped into a pit with significant pollution.
An object of the present invention is to provide a closed loop process for treating contaminated clays, sands, fines, gravels, drilling cuttings, or other solids or particulate containing fluids to produce an environmentally acceptable product.
The present invention also has as an object to provide a closed loop system for effectively removing oil, salt water residue, diesel or other contaminants produced by the drilling operation so that they are separated from the cuttings produced in the drilling process and are not otherwise dumped into the environment, as in the prior art.
Another object of the invention is to avoid the onerous expense of hauling contaminated cuttings and particulate materials from reserve pits or tanks to hazardous waste disposal locations which may be hundreds of miles from the well being drilled.
Another object of the invention is to provide a closed loop process for the treatment of particulate materials which is effective to remove, reduce and separate both chlorides and hydrocarbons from such materials, using only a small amount of water and leaving an environmentally acceptable product.